Studies of victimization show that lesbian, gay, and bisexual (lgb) youths are often victim of different kinds of attack. Little research to date has investigated the impact of victimization based on sexual orientation on lgb youths' mental health. Available research suggests vulnerability in this population, including an elevated risk of suicidality. Using a longitudinal design following a diverse sample of youths aged 15 to 20 over a two-year period, this project will investigate the mental health consequences of victimization, especially sexual orientation victimization. A large group of lgb youths from the New York City metropolitan area and from suburban Long Island and Westchester County will be sampled from community-based organizations serving lgb youths. Another group of lgb youths not affiliated with these organizations will also be recruited. An initial group of 500 lgb youths (250 females and 250 males, from different racial/ethnic groups) will be recruited. A final sample size of 405 youths will be available for analysis. Participants will complete extensive self-administered questionnaires, and will be interviewed by trained project assistants. We hypothesize that current victimization has a deleterious effect on lgb youths' adjustment based on youths' personal vulnerability at the time of victimization and their exposure to other stressors. Past vulnerability will be high if youths have a history of psychiatric disorder, of suicidality (suicidal thinking and attempts), and of past victimization. Past victimization includes victimization based on youths' sexual orientation, victimization based on their racial or ethnic background, physical abuse, sexual abuse, victimization by dating partners, exposure to crime, and exposure to other traumatic events. Current stressful life events include stressors particular to lgb youths, especially negative family reactions to youths' sexual orientation. Under conditions of high personal vulnerability and exposure to many stressful life events, victimization of lgb youths leads to traumatic stress reactions, and, in turn, to mental health problems. The relationship between victimization and mental health is mediated by self-esteem, social support, and coping skills. Youths with high self-esteem, high social support, and effective coping skills will not suffer the negative consequences of victimization. The project will answer these questions: 1) What kinds of victimization do lgb youths experience? 2) What mental health problems (psychiatric disorders, behavioral problems, and suicidality) occur among lgb youths? 3) Under what conditions does victimization lead to the development of mental health problems? 4) What characteristics of youths distinguish those who cope successfully with victimization from those who develop mental health problems? 5) What characteristics of youths-especially their victimization history, pre-existing psychiatric disorders, and suicidality history--relate to high risk for future suicide attempts?